3) Gradient unlearning method.
The third group focuses on approximating the SGD steps as if full retraining was performed [1]}, [2]}, [3]}, [4]}.
To aid in a history of accurate computations to produce an effective approximation, the unlearning method periodically computes the exact gradient after some iterations.
The exact gradient is computed on the remaining training data \(\mathbf {D}\) -\(\mathbf {D_i}\) .
